Treatment of complex cobaltic ores



Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE No Drawing. Application September 28, 1929, Serial No. 396,011, and in Spain March 30,

3 Claims. (01. 204-15) The invention relates to an electrolytic process for the treatment of complex cobaltic ores for obtaining the separation of the cobalt. It also relates to the treatment of minerals in alkalineearth gangue which besides cobalt contain copper.

Accordingto this process the mineral is submitted at first to the simultaneous action of sul phuric acid and chlorideof sodium. The solution thus obtained is then submitted to electrolysis in order to eliminate the copper. The liquid which has served as the electrolyte is concentrated by evaporation, then cooled in such manner that the alkaline-earth substances are precipitated. The liquid is then again submitted to evaporation in order to concentrate it, then to cooling, after which the cobalt separates in the form of crystals of cobalt sulphate. The sulphate is then dissolved and the solution is submitted to electrolysis.

The process is carried out in the following manner: By means of sulphuric acid diluted with water and of a part (such for example as 5%) of chloride of sodium the metallic constituents of the ores are attacked.

Where there remains some part of the metal which has not taken part in reaction with the sulphuric acid and chloride of sodium, because it was combined with arsenides or sulphocyanides in the ore or in some other constituents not susceptible to reaction with the acid, this part would be oxidized in a furnace for rendering it attackable and it may then be passed into the main bath or may be separately subjected to treatment with acid.

When all the metals are extracted from the ore the solution of the metals is electrolyzed in suitable vats constructed for example of wood lined with lead. In this operation it is necessary to exercise care that the concentration of the 40- liquid is fr om about 13 to 15 Baum in order to avoid-a substantially higher concentration and that iron shall not be precipitated from the solution.

With lead anodes or with anodes of copper rendered inactive by preliminary treatment with nitric acid or with anodes of other metal rendered inactive by treatment in a bath of an acid solution of a mercury compound and with cathodes of thin sheet copper in order that there may be formed upon them electrolytic copper or oxide, and operating with two volts for each vat and at 0.60 ampere per square decimetre of surface of the cathodes, all of the copper is extracted from the solution which thus only contains the other metals.

Separation of cobalt. The liquid resulting from the operation described containing no copper is conducted to boilers'or vessels for the concentration of the liquid by heating and there submitted to evaporation until a concentration of about 28 Baum is reached as indicated by the acidometer. The liquid is then caused to pass into reservoirs made of wood and lined with lead in which it is slightly cooled-whereby the whole content of earth-alkaline salts are precipitated as a result of the concentration by heating. The liquid is then filtered and again passed to the boilers or vessels in order that it may be further concentrated to a degree of about 38 Baum as indicated by the acidometer. The concentrated liquor is then conducted to cooling reservoirs in which cobalt crystallizes in the form of sulphate separating from the nickel and the iron which still remains in the solution.

The cobalt can be extracted from the sulphate obtained as follows: To the sulphate of cobalt diluted with water until the-acidometer mark is from about 9 to 10 Baum there is added a quarter of its weight of sulphate of ammonia and neutralization is effected with the ammonia. Further, there isadded in order that it may be slightly acidified and thus better to conduct the current, a little of citric acid; the liquor is made up in vats of wood lined with'lead within which anodes of graphite or of inoxidizable steel or other metal rendered quite inactive and with cathodes of copper-chrome. In the electrolysis the cobalt will be deposited in the form of thin scales which will be precipitated in the bottom of the vat. A current of 2 volts should be used to commence and soon after it may fall to two volts and at 0.60 ampere per square decimetre of the surface of the cathodes.

I claim;- I 1 1. A process for extracting cobalt from complex metals in alkaline earth gangue and containing copper, consisting in submitting the ores to the action of sulphuric acid and sodium chloride for attacking the metal contents of the ore, electrolyzing by the use of anodes of unattackable material and cathodes of thin sheet copper the solution thus obtained until all the copper has been eliminated, concentrating by evapora tion the whole of the liquid which has served as the electrolyte, the concentration being effected to a degree to favour the precipitation of alkaline earth salts, filtering the liquid, further concentrating it by evaporation and subsequently cooling it in order that the content of cobalt may separate in the form of crystals of sulphate of cobalt, the degree of concentration being regulated to favour the crystallization, then dissolving the sulphate of cobalt and submitting the solution to electrolysis for the decomposition of metallic cobalt.

2. A process for extracting cobalt from complex minerals in alkaline earth gangue and containing copper, consisting in submitting the ores to the action of sulphuric acid and sodium chloride for attacking the metal contents of the ore, electrolyzing the solution thus obtained in order to eliminate copper, treating the electrolyte by evaporation for its concentration, then by cooling for the precipitation of alkaline earth salts, then by further concentration by evaporation, and subsequent cooling, in order that the content of cobalt may crystallize in the form of sulphate, treating the sulphate of cobalt by dilution with water and the addition thereto 0! sulphate of ammonia, neutralizing with the ammonia and acidifying with citric acid and electrolyzing with the aid of anodes or inactive material and cathodes of copper chrome for the separation of cobalt.

3. A process for extracting cobalt from complex minerals in alkaline earth gangue and containing copper, consisting in submitting the ores to the action of sulphuric acid and sodium chloride, oxidizing in a furnace those parts of the metallic contents of the ore which are not attackable by the acid and sodium chloride in order to render them so attackable, submitting such treated ore also to the action of sulphuric acid and chloride of sodium, electrolyzing the whole of the solution thus obtained until all the copper is eliminated, treating the whole of the electrolyte by evaporation until it has acquired a definite concentration, then by cooling effecting the precipitation of the alkaline earth salts, then by further concentration by evaporation, concentrating the electrolyte to a degree to favour the crystallization of cobalt, subsequently cooling to effect the crystallization of the cobalt in the form of sulphate, treating the sulphate of cobalt by dilution with water to secure a definite degree of concentration, adding sulphate of ammonia, neutralizing with the ammonia and acidifying with a small addition of citric acid and subjecting the solution to electrolysis for the separation of the cobalt.

RICARDO SANZ CARRERAS. 

